In reply to Mark Lundin.

I think it depends on your application. Mathematically, a non-PD matrix does not generate a metric and the resulting formula does not satisfy the axioms of a distance. At the same time, in factor analysis, you often estimate a matrix that might not be PD so this case does arise in practice. In that case the estimate of the "Total variance" can be greater than 1. See the doc for PROC FACTOR or this page: http://support.sas.com/documentation/cdl/en/imlsug/63546/HTML/default/viewer.htm#imlsug_ugmultfactor_sect001.htm
I am not an expert on factor analysis, but it seems to me that the problem is that the ESTIMATES are not PD and so statisticians try to jump through loops to make sense of something that is (I think) inherently nonsensical.